The Atmos clock is very sensitive and can react significantly to very minor adjustments. If the clock is running too fast or too slow, use the adjustment lever on the top of the frame which is just behind the dial at the twelve o clock position. Moving the lever anti clockwise this speeds up the clock and turning the know clock wise slows down the clock. The lever is marked A for advance (speed up) and R for retard (slow down). Move the lever half a turn and wait several days or a week for the clock to adjust and if necessary repeat.